The present technology relates to an optical element, a projection type image display apparatus which is provided with the same, and an original recording for manufacturing the same. In more detail, the present technology relates to an optical element which is used in phase difference compensation for liquid crystal panels or the like, a projection type image display apparatus which is provided with the same, and an original recording for manufacturing the same.
Projector apparatuses (projection type image display apparatuses) which realize a large screen by enlarging and projecting an image onto a screen are utilized in a wide range of fields. In recent years, so-called liquid crystal projector apparatuses which perform projection onto a screen by optically modulating light which is emitted from a light source with a liquid crystal display apparatus are particularly common. The liquid crystal display apparatus displays images in a display mode which corresponds to the type of liquid crystal molecules which are used in the liquid crystal panel.
For example, Vertically Aligned (VA) mode liquid crystal display apparatuses where liquid crystal molecules which have a negative dielectric anisotropy are sealed with perpendicular light distribution between a pair of substrates which configure a liquid crystal panel are widely used. In the VA mode liquid crystal display apparatuses, since the liquid crystal molecules are aligned to be substantially perpendicular with respect to the main surface of the substrates when no electric field is applied, light passes through the liquid crystal layer and hardly changes the polarization plane thereof. Accordingly, by installing polarizing plates above and below the substrate, a favorable black display is possible when no electric field is applied. The VA mode liquid crystal display apparatus has the advantage that it is possible to realize a high contrast in comparison with a Twisted Nematic (TN) mode liquid crystal display apparatus.
In the VA mode liquid crystal display apparatus, birefringence is obtained by inclining and aligning the liquid crystal molecules when an electric field is applied. Therefore, when no electric field is applied, the liquid crystal molecules are aligned to have a minute inclination angle (pre-tilt angle) in advance. In this manner, since the liquid crystal molecules are not completely perpendicular with respect to the main surface of the substrates when no electric field is applied and the alignment is slightly inclined, residual phase difference is generated in the liquid crystal panel. Accordingly, the polarization plane of the incident light from the perpendicular direction is slightly rotated and, as a result, the contrast is decreased by the generation of light leakage from the polarization plate.
Here, a technique is proposed which uses a phase difference compensation plate where the amount of phase difference in the in-plane direction is small to compensate for the residual phase difference in the liquid crystal panel and obtain a high contrast. The amount of phase difference of the phase difference compensation plate is different according to the liquid crystal panel to be used; however, a small phase difference amount of 30 nm or less is desirable. As phase difference compensation plates which have small phase difference amounts, phase difference compensation plates not in the related art have been proposed.
Japanese Unexamined Patent Application Publication No. 2008-70666: A phase difference compensation plate formed of a body obtained by combining an optical multilayer film where a plurality of layers with different refractive indices are laminated in a regular order and a polymer film is proposed.
Japanese Unexamined Patent Application Publication No. 2007-11280: Imparting an anti-reflection function to a phase difference compensation plate by providing an anti-reflection film on the surface of the phase difference compensation plate is proposed.